Field of the Invention
The field of the invention is related to a system and assembly method for a fluid pump device for use in a continuous multi-fluid delivery system having applications in medical diagnostic and therapeutic procedures wherein one or more fluids are infused/injected into a patient.
Description of Related Art
In the medical field, fluid delivery devices used to provide fluids to patients are generally well-known and exist in many different forms. A system commonly used for this purpose is a gravity-feed system wherein a fluid containing bag is supported above the level of the patient's body and wherein the flow rate to the patient is controlled by the gross pressure of a clamp upon the flexible tube extending between the bag and the patient. It will be readily understood that the flow rate of fluid through the tube is a function of the amount of constriction of the tube. Manually operated devices are known in the medical field for delivery of fluid under pressure to a patient. Examples of such manually-operated pumping devices are known from U.S. Pat. No. 3,464,359 to King et al.; U.S. Pat. No. 2,062,285 to Bergman; and U.S. Pat. No. 1,748,810 to Wandel, as examples.
Syringe-based infusion pumps and peristaltic pumps have also been used in the medical field for delivering fluids to patients under pressure and provide more precise control over the flow rate and volumetric delivery of fluids to patients. An example of a syringe pump adapted to deliver fluid to a patient is described in U.S. Pat. No. 5,529,463 to Layer et al., which discloses a multi-syringe pump for this purpose. A peristaltic pump system suitable for delivering a constant flow of fluid under pressure to a patient is described in U.S. Pat. Nos. 6,558,125 and 6,488,660, both to Futterknecht.
There are a number of medical procedures which require the delivery of fluids to a patient in a precisely controlled manner. One such application involves the delivery of contrast media fluid to a patient during a diagnostic computed tomography (CT) scan to provide enhanced x-ray images. Traditionally, such contrast media fluid has been delivered to the patient using a syringe-based injection system. Such injection systems require the contrast media fluid to be transferred from its original container to a disposable syringe. The injection system then pressurizes the fluid within the syringe to deliver the fluid to the patient at a controlled flow rate, precisely when needed. Some syringe-based injection systems are capable of accommodating two separate syringes to facilitate sequential or simultaneous delivery of two different types of fluid.
One limitation of a syringe-based fluid injection system is the need to refill and replace the disposable syringes prior to each patient procedure. U.S. Pat. No. 5,806,519 to Evans, III et al. describes a fluid delivery system which could be used to deliver fluid to multiple patients in succession without the need to refill and replace syringes for each patient. Another fluid delivery system that purports to overcome this limitation is disclosed in U.S. Pat. Nos. 6,558,125 and 6,488,660 (Futterknecht). These latter patents disclose a fluid delivery system that utilizes a peristaltic pump to deliver fluid directly from contrast media bottles to the patient. While this system eliminates the need to replace disposable syringes after each patient, the use of a roller-type peristaltic pump inherently limits the pressure capability of the system to approximately 200 psi. Unfortunately, many CT procedures and virtually all angiographic procedures require fluid to be delivered at higher pressures.
In order to provide more precise control of flow rates and volumetric delivery of fluids to patients, positive displacement pump platforms have been developed in the medical field. These devices eliminate the use of syringes and provide increased pressure ranges over peristaltic pumps. One such positive displacement pump device is disclosed in U.S. Pat. Nos. 5,196,197 and 6,197,000 to Reilly et al., which describe a system for the continuous delivery of contrast media fluid to a patient that uses a cam-driven multi-piston pump. Such a pump is capable of delivering fluids at relatively high pressures in a controlled manner. Another example of a positive displacement pump platform intended for use in delivering fluid to a patient undergoing a medical procedure is disclosed in International Publication No. WO 2006/056828, which discloses a volumetric pump with reciprocating and rotating pistons that are adapted to deliver a controlled and continuous flow rate of fluid during a medical procedure. Japanese Publication Nos. JP 61-42199 and JP 61-4220, both assigned to Nemoto Kiyourindou KK, disclose another multi-piston cylinder pump which enables the controlled and continuous delivery of fluids during a medical procedure.
There are several disadvantages present in positive displacement pump platforms known in the medical field for fluid delivery to a patient. One disadvantage is that these pump platforms are, typically, limited to pumping a single fluid type. Many medical procedures, such as CT procedures, often involve the use of a combination of contrast media fluid and saline delivered precisely to the region of interest within a patient's body. For example, after an initial injection of contrast media fluid is performed, a bolus of saline fluid may be administered to move the contrast fluid into the region of interest. In order to have the capability of delivering two or more different types of fluids, an external selection valve (such as a stopcock) must be added upstream of the pump inlet to allow the fluid delivery system to select from one of two (2) or more available fluid sources or possibly both if a mixing device is also provided. If two (2) interconnected pumps are present in the fluid delivery system, a downstream mixing device is required in such a two-pump system.